The present invention concerns generally concerns the construction of vehicles such as snowmobiles, all terrain vehicles (xe2x80x9cATVsxe2x80x9d), and other similar vehicles. More specifically, the present invention concerns the construction of a front suspension with three-ball joints that are connected to a support leg for the vehicle.
Snowmobiles, ATVs, wheeled vehicles, and other related vehicles (hereinafter, xe2x80x9crecreational vehicles,xe2x80x9d although the appellation should not be construed to be limited only to the vehicles or type of vehicles described herein) often function under similar operating conditions. Despite this, snowmobiles, ATVs, wheeled vehicles, and other recreational vehicles do not share a common design approach or a commonality of components. This is due, in large part, to the different stresses and strains (mainly at the extremes) that the different vehicles experience during routine operation.
As a general rule, the prior art includes few, if any, examples of a common design approach to ATVs, wheeled vehicles, and snowmobiles. Primarily, this appears to be due to the fact that these vehicles were designed traditionally from radically different starting points. For example, there has not been a common design approach to the front suspensions that are incorporated into snowmobiles, ATVs, and other wheeled vehicles even though there are common design parameters for each of these types of vehicles.
In the case of snowmobiles, two front suspensions are well known in the art. The first is typically referred to as a xe2x80x9ctrailing arm suspensionxe2x80x9d and is commonly found on snowmobiles manufactured by Bombardier Inc. of Montreal, Quebec, Canada. The second is known as a double A-arm suspension and is typically found on snowmobiles manufactured by Arctic Cat of Thief River Falls, Minn., USA.
A prior art trailing arm front suspension is generally depicted in FIGS. 1, 3, and 36. As illustrated in detail in FIG. 36, a trailing arm suspension 442 includes a trailing arm 444 (which is also referred to as a swing arm). Trailing arm 444 connects between a pivot 446, which connects to engine cradle 56, and a front leg 448. Front leg 448 connects ski 20 to engine cradle 56. A shock absorber 450 connects between engine cradle 56 and trailing arm 444 to dampen the forces associated with the travel of snowmobile 12 over uneven terrain. Steering control of snowmobile 12 is provided by a mechanical link between skis 20 and handlebars 82.
A typical double A-arm suspension 452 is illustrated generally in FIGS. 37-40. The illustration of double A-arm suspension 452 that is shown in FIGS. 37-38 was reproduced from U.S. Pat. No. 5,664,649, which purports on its face to be assigned to Arctic Cat. As shown, double A-arm suspension 452 includes an upper A-arm 454 and a lower A-arm 456. Both A-arms 456, 454 are connected to front leg 458 and permit front leg 458 to move vertically as snowmobile 460 travels over uneven terrain. A shock absorber 462, which is connected between the body of snowmobile 460 and lower A-arm 456, dampens the forces applied to skis 464 as snowmobile 460 travels over the ground. Alternatively, it is known to connect shock absorber 450 directly to front leg 458, as illustrated in FIG. 39.
Since upper and lower A-arms 454, 456 are connected to front leg 458 through pins (or bolts) 466, 468, front leg 458 cannot rotate around its vertical centerline. Therefore, front leg 208 cannot be used to turn ski 464. Instead, a steering shaft 470 extends through a hole 472 bored through front leg 458. Steering shaft 470 is connected to handlebars 474 through a mechanical linkage 476. As handlebars 474 are rotated, steering shaft 470 rotates in the direction of the arrow 478 shown in FIG. 40. Since steering shaft 470 is connected to ski 464 through a pin or bolt 480, as steering shaft 470 rotates, ski 464 turns.
While both of these front suspensions provide adequate control and steering of the respective snowmobiles on which they are installed, neither provides a simple construction for a front suspension.
In the case of the trailing arm suspension, the trailing arm 444 adds additional components to the system. The additional components add to the manufacturing cost and to the complexity of snowmobile 12. Moreover, the additional components increase the overall weight of snowmobile 12.
In the case of double A-arm suspension 452, the same is true. In this case, however, the complexity of the system and the weight of the components are particularly pronounced. For example, it is estimated that the weight of front leg 458 is about twice that of front leg 448 of trailing arm suspension 442. This is attributable to the individual components that comprise front leg 458, which is usually constructed as an aluminum extrusion. Steering shaft 470, which is typically made of steel and forms a part of front leg 458, is disposed through front leg 458 to provide steering for snowmobile 460. Steering shaft 470 adds to the overall weight of front suspension 452.
The complexity of front leg 458 is attributable not only to the design of the component but also to the considerable amount of machining and assembly that are required after front leg 458 is extruded. For example, hole 472 must be drilled through front leg 458 to accommodate steering shaft 470. Moreover, three holes 482, 484, and 486 must be drilled through front leg 458 to accommodate upper A-arm 452, lower A-arm 454, and shock absorber 462. In addition, while not shown in the drawings, a hollow shaft is welded between the sides of front leg 458 to accommodate the pins (such as pin 466) that connect upper A-arm 454, lower A-arm 456, and shock absorber 462 to front leg 458. A bushing is usually placed within the hollow shaft to facilitate pivoting motion of the pins inserted therethrough. All of this adds considerably to the overall weight and construction cost of snowmobile 460.
In the manufacture of snowmobiles (as with the construction of any product), one goal is to reduce the weight of the final vehicle. Another object is to reduce the complexity of the vehicle. Both goals ultimately reduce the overall manufacturing cost of the vehicle.
The inventors of the present invention recognized that a hybrid approach between the two prior art suspensions might accomplish both of these objectives. Namely, a hybrid approach might provide both a more simplified construction and a lower weight for a front suspension. In addition, the inventors recognized that such a hybrid approach might provide a front suspension that could be applicable both to snowmobiles, wheeled vehicles, ATVs, and other recreational vehicles.
No prior art front suspension, however, offers or suggests a practicable approach.
In view of the foregoing, one object of the present invention is to exploit the design elements of a snowmobile that are easily and readily transferred to the design of a wheeled vehicle, such as an ATV, based on a basic frame structure.
To that end, one object of the present invention is to provide a front suspension that incorporates a double A-arm construction which does not require a heavy, front leg with a steering shaft disposed therein.
It is another object of the present invention to provide a front suspension for a snowmobile, wheeled vehicle, or ATV that does not require a trailing arm.
Accordingly, it is an object of the present invention to provide a front suspension with a light-weight leg that is rotatable about a vertical axis.
It is still another object of the present invention to provide a suspension for a vehicle that includes an upper A-arm and a lower A-arm. The suspension further includes a leg with a vertical axis that is rotatably connected to both the upper A-Arm and the lower A-arm. A mechanical link is rotatably connected to the leg so that movement of the mechanical link applies rotational force to the leg to cause the leg to rotate about the vertical axis.
Another object of the present invention is to provide a suspension further including a first ball joint connecting the upper A-arm to the leg, a second ball joint connecting the lower A-arm to the leg, and a third ball joint connecting the mechanical link to the leg.
A further object of the present invention is to provide a suspension where the leg is an aluminum extrusion with the direction of the extrusion perpendicular to the vertical axis of the leg.
Another object of the present invention is to provide a suspension where the leg is squeeze-cast aluminum.
A further object of the present invention is to provide a snowmobile and a wheeled vehicle, such as an ATV, including such a suspension.
Still other objects of the present invention will be made apparent by the discussion that follows.